How do I REALLY free up a lot of space on my ps3 HDD

I know there are a lot of posts relating to freeing up space on my ps3 all over the net, but I'm not looking for a dummies guide, I'm looking for a more advanced guide.

From what I can tell I am only using about 10gb of the space on my ps3, no media except for 4 very small pics, only the game data files and save data files relevant to the games I currently play and this 10gb includes those (its skyrim and bf3 btw).

However on my 40gb ps3 it still says I have only 12gb free, where is the other 15gb, I've tried loads, including: going into safe mode, trawlling through every file on my ps3 (I'm quite good and keep it relatively free of junk) but still cant free up more than 10gb.

Any ideas from anyone would be much appreciated. I don't want to have to upgrade my internal HDD or anything at the moment as I don't have the money to do that.

Re: How do I REALLY free up a lot of space on my ps3 HDD

My mate had one of these 40gb PS3's, from memory allowing for the difference in how HDD space is calculated and the operating system I think his showed a usuable space of about 31gb straight out of the box

Re: How do I REALLY free up a lot of space on my ps3 HDD

important thing to note tho with upgrading the HDD is the optimal spin speed for a ps3 HDD is 5400rpm you can get faster but risks of overheating are significantly increased and dont make the same mistake I made 1st time by buying a 3.5" SATA HDD it needs to be 2.5"